Combination dissector and expander

ABSTRACT

A combination tissue dissector and long term expander is disclosed for use in plastic surgery applications and other applications where it is desirable to dissect a tissue pocket and serially expand the dissected pocket through long term tissue expansion. The combination device performs the separate functions of dissection and long term expansion in a single balloon package. In an exemplary embodiment, three sheets of substantially inelastic material are bonded together at their outer margins to form two discrete inflatable chambers. The lower inflatable chamber defined by the middle and lower balloon sheets is further welded together at various points over the sheet&#39;s surface area to create a semi-rigid base portion which provides a flat well-defined footprint for the balloon. The semi-rigid base prevents further enlargement of the tissue pocket at the margins when the device is utilized as a tissue expander. In a preferred method of use for the combination device, the combination device is tunneled bluntly to a desired location within the body. The device is then inflated to dissect tissue layers along natural tissue planes and create a tissue pocket. After dissection, the combination device may be left within the body as a temporary implant to further expand the tissue pocket through long term expansion until the desired tissue pocket volume is achieved.

This is a continuation-in-part of U.S. application Ser. No. 08/726,072filed on Oct. 3, 1996 now U.S. Pat. No. 5,776,159, the disclosure ofwhich is expressly incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention pertains generally to the field of surgicalapparatus and methods for use in creating an anatomic working space andthereafter expanding the space. More particularly, the present inventionpertains to an inflatable balloon dissector and its methods of usewherein a single balloon device combines the function of tissuedissection with long term tissue expansion.

BACKGROUND OF THE INVENTION

In the past, inflatable devices have been utilized to dissect tissuelayers to create an anatomic working space to facilitate the performanceof laparoscopic or other minimally invasive surgical procedures. Forexample, in commonly assigned U.S. Pat. No. 5,514,153 to Peter M.Bonutti, the disclosure of which is hereby incorporated by reference inits entirety, various inflatable devices are disclosed which can beutilized to dissect tissue to create an anatomic working space. Asurgical balloon dissector and its methods of use are also disclosed incommonly assigned U.S. Pat. No. 5,496,345, to Kieturakis et al., thedisclosure of which is also hereby incorporated by reference in itsentirety. It has been found that a tissue pocket formed by balloondissection is generally more regular and precise than the pockettypically obtained with manual dissection. In contrast to traditionalblunt dissection techniques, the dissecting balloon creates a tissuepocket while respecting natural tissue planes or boundaries in theanatomy.

A second class of inflatable devices known as tissue expanders are fluidoperated devices which, when inflated, stretch and place pressure onoverlying tissues to create tissue growth in a localized area of thebody. Tissue expanders have generally been used in plastic orreconstructive surgery as temporary implants to gradually expand apreviously dissected pocket over time as the overlying skin and tissuegradually alters (through new cell formation) and expands in response tothe force applied by the inflatable tissue expander. Often, the"created" tissue is stretched over an adjacent area where a tissuedefect has been removed or where additional tissue is required. Tissueexpanders traditionally incorporate inflation ports which are connectedby an inflation tube to the expander and are implanted somewhat remotefrom the expansion site. The inflation ports are small reservoirs whichincorporate a self-sealing membrane through which fluid may beintroduced by hypodermic needle. The port is placed under the skin suchthat there is easy needle access to the membrane.

In the conventional use of tissue expanders, it has been customary tomake an incision immediately adjacent to or over the region into whichthe expander is to be subsequently placed, and then to utilize a bluntinstrument or the finger to dissect exposed tissue layers to create apocket. Generally, it is desirable to dissect the pocket adequately suchthat the dissected footprint easily accommodates the expander withoutcurling the edges of the expander at the dissection margins. Once theexpander is placed into the dissected space, the incision through whichthe dissection and expander placement was accomplished is closed andallowed to heal before the expansion process begins. This step isnecessary because the tissue strength at the incision must bereestablished in order to withstand the stresses caused by long termtissue expansion. Otherwise, there is chance that the expander willextrude out of the incision preferentially to expanding the tissue overthe dissected footprint, as desired. This healing step may requireconsiderable time (on the order of weeks) before tissue expansion canbegin.

Recently and commensurate with the trend toward minimally invasivesurgery, practitioners have begun inserting tissue expanders intopreviously dissected pockets in the body through incisions remote fromthe expansion site such that the lengthy incision healing step can beeliminated. This advantageously allows expansion to be commencedimmediately after placement of the tissue expander. Use of a remoteinsertion site also requires dissection to be accomplished through theremote incision and that the expanders are capable of being rolled orotherwise compacted to allow for proper placement at the remote sitethrough the incision.

In the tissue expander art, it is also known that excessive inflationpressures in the tissue expander can cause tissue necrosis. Hence, theinflation pressure of the tissue expander must be moderated to avoidnecrosis. Because the pressure must be held beneath the necrosis level,tissue expanders are left in place over a prolonged period of time toallow the subcutaneous tissues to gradually alter and expand. Thisrequires monitoring and periodical adjustment of the fluid volume in theexpander as the tissue gradually stretches over time.

In certain surgical procedures, especially in plastic surgeryprocedures, it is necessary to dissect a tissue pocket for the laterimplantation of a prosthetic device. For example, breast augmentationand reconstruction procedures involve dissecting a space or pocket inthe breast and, if necessary, following the dissection step with longterm tissue expansion to enlarge the pocket to receive the desiredimplant. Previously, two or more different devices have been required toperform the dissection and expansion steps.

Johnson et al., U.S. Pat. No. 5,258,026, discloses a surgical procedurefor breast augmentation. In Johnson, an incision is made in theumbilicus and an elongate hollow tube carrying an inflatable prothesisis tunneled above the chest wall to a position behind the breast. Theprothesis itself is then utilized as a tissue dissector by overinflatingthe prosthesis to 150% of its anticipated ultimate fill volume to createthe breast pocket. The prothesis is then reduced in volume to itsintended final volume and left in place. The umbilical incision is thenclosed and the surgery completed. While Johnson discloses the use of aninflatable member to create a tissue pocket in the breast for thepurpose of augmentation, Johnson uses the implant itself to dissect anddoes not provide a device or method for further expanding the tissuepocket through long term expansion should the size of the initiallydissected space be insufficient.

Accordingly, there is a need for an improved device and associatedmethods of use which incorporate the features of a tissue dissector andlong term tissue expander in a single device to overcome theaforementioned disadvantages in the prior art.

SUMMARY OF THE INVENTION

The present invention provides a combination device wherein a commonfluid operated bladder (or compound bladders) may perform the distinctfunctions of tissue dissection and long term tissue expansion in serialorder. The present invention preferably utilizes a substantiallyinelastic balloon formed from a urethane material, for example, todissect tissue layers to create a tissue pocket or working space, andthereafter to provide long term tissue expansion if desired.

A combination dissector/expander according to the invention may be anyone of the balloon dissectors described in commonly assigned co-pendingapplication Ser. No. 08/570,766, with appropriate modification toprovide for an implantable self-sealing fill valve and provided thatwhen the fluid volume is reduced appropriately after dissection, theballoon remains at a positive pressure. Suitable self-sealing valveswhich may be temporarily implanted (also known as injection ports) areknown in the art and will not be described in detail herein. One exampleof a suitable self-sealing valve for use with a combinationdissector/expander as disclosed herein is manufactured by CUIcorporation, Santa Barbara, Calif., as part of a saline fill tissueexpander. As disclosed in commonly assigned application Ser. No.08/570,766, the disclosure of which is hereby incorporated by referencein its entirety, the balloon carried by the tunneling member ispreferably rolled, folded, inverted, and/or otherwise gathered about thetunneling member to provide a compact device. In several of theembodiments disclosed in application Ser. No. 08/570,766, provision ismade for the use of a scope to permit observation within the body bothas the device is tunneled to a desired location within the body wheredissection is to occur and thereafter during balloon expansion as thetissue layers are dissected. For example, an internal scope cover canserve as a tunneling member, and could provide visualization duringtunneling and/or dissection. However, in plastic surgery applications itis usually not necessary to provide for visualization because suchoperations are often performed in the physician's office rather than thehospital and visualization equipment, i.e., scopes and televisionmonitors, are oftentimes unavailable.

A first preferred combination dissector and expander is formed fromthree sheets of material bonded together at the outer margins of thesheets to form two discrete inflatable chambers. The top and middlesheets define a first inflatable chamber therebetween which is bonded atthe common periphery of the sheets. The bottom and middle sheets arefurther bonded together at various points over their common surface areaand define a separately inflatable semi-rigid chamber. Either chambermay be used as a tissue dissector, and the semi-rigid chamber provides astable footprint for the device when it is utilized as a tissue expanderto help avoid unwanted enlargement of the pocket at the dissectionmargins.

In a preferred method of use directed to plastic surgery applications,particularly breast augmentation and reconstruction, a combination fluidactuated dissector/expander is introduced, preferably by blunttunneling, to a location where it is desired to create a tissue pocket.The balloon associated with the combination device is then inflated todissect tissue layers and create the tissue pocket. After dissection, ifthe dissected pocket is not large enough to accommodate the desiredprosthesis, the fluid volume (or pressure) of the combination device maythen be adjusted to a level appropriate for long term tissue expansion.The combination tissue dissector/expander may be left in place over theamount of time required to achieve the desired amount of tissueexpansion as is known in the tissue expander art, and the balloon fillvolume (or pressure) adjusted over the period of time required toachieve gradual tissue expansion.

These and other aspects, features, objects, and advantages of thepresent invention will be more fully understood and appreciated uponconsideration of the following detailed description of a preferredembodiment of the invention, presented in conjunction with theaccompanying drawings wherein like reference numerals designatecorresponding parts in the several figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the anatomy of the human breastincluding the subcutaneous layers down to the rib cage.

FIG. 2a is a cross-sectional view similar to FIG. 1 of the human breastillustrating a balloon in accordance with the present invention beingutilized to form a tissue pocket between the pectoralis major muscle andglandular breast tissue.

FIG. 2b is a view similar to FIG. 2a illustrating a balloon inaccordance with the present invention being utilized to form a tissuepocket between the chest wall and the pectoralis major muscle overlyingthe chest wall.

FIG. 3 is a top view of a preferred embodiment of a combination tissuedissector and expander in accordance with the present invention.

FIG. 4 is a cross-sectional view of the combination tissue dissector andexpander illustrated in FIG. 3 taken along the lines labeled 4.

FIG. 5 is a perspective view of an alternative embodiment of acombination tissue dissector and expander in accordance with the presentinvention.

FIG. 6 is a cross-sectional view of the combination tissue dissector andexpander of FIG. 5 along line 6--6.

FIG. 7a is a cross-sectional view taken along line 7--7 of FIG. 5showing an external seam of the balloon prior to inverting the balloon.

FIG. 7b is a cross-sectional view taken along line 7--7 of FIG. 5showing a preferred embodiment of the inverted seam of the balloon.

FIG. 8 is a top view of the alternative embodiment of the combinationtissue dissector and expander of FIG. 5 with the distal end invertedinto the balloon.

FIG. 9 is a cross-sectional view of the alternative embodiment of thecombination tissue dissector and expander with the balloon inverted androlled around a tunneling shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While principally described in terms of breast augmentation, the presentinvention may also be used in connection with other surgical procedures,including, but not limited to, brow lifts and scar tissue removal, forexample.

FIG. 1 illustrates a cross-sectional view of the anatomy of the humanfemale breast 8. The breast 8 consists of a mound of glandular tissue 10which is primarily fat. A layer of skin 11 covers the glandular tissue10. The pectoralis major muscle 25 overlies the pectoralis minor muscle22 and a portion of the chest wall 27 and ribs 24. A layer of pectoralfascia 14 lies between the overlying glandular breast tissue 10 and thepectoralis major muscle 25. The pectoral fascia 14 defines a naturallyoccurring tissue plane within the human body which may be bluntlydissected to create an anatomic working space or breast pocket. Asdiscussed in application Ser. No. 08/570,766, balloon dissection alongsuch naturally occurring tissue planes is desirable in that a virtuallybloodless operating space may be created between the tissue planes.

Continuing with the description of the anatomy of the breast, a layer ofdeep pectoral fascia 28 sheaths the underside of the pectoralis majormuscle 25 and separates the pectoralis major muscle 25 from the chestwall 27 and the pectoralis minor muscle 22. As will be explained below,like the pectoral fascia 14, the deep pectoral fascia 28 defines anaturally occurring tissue plane which may be bluntly dissected tocreate a tissue pocket between the pectoralis major muscle 25 and thechest wall 27.

In the general use of a combination dissector/expander, an incision isfirst made in the body at a location appropriate for the procedure andthe combination device with a deflated balloon is tunneled bluntly to adesired location within the body as described in copending applicationSer. No. 08/570,766, for example. In the case of breast augmentation orreconstruction, for example, several different incision sites may beappropriate depending on the surgical approach utilized.

A first approach in a breast augmentation procedure is to make anaxillary incision and to utilize a combination device according to theinvention to tunnel medially and interiorly from the axillary incisionto a desired location underlying the glandular breast tissue, eitherbetween the chest wall and pectoralis major muscle or between thepectoralis major muscle and the glandular breast tissue. When asubglandular implant is desired, the combination dissector/expander ispreferably advanced along the layer of pectoral fascia 14, separatingthe layer in the process, until the balloon 32 associated with thedevice reaches the desired position beneath the glandular breast tissue10. (See FIG. 2a). If a subpectoral implant is desired, a combinationdissector/expander can be tunneled bluntly along the deep pectoralfascia layer 28 below the pectoralis major muscle 25 and above the chestwall 27 to the desired location as shown in FIG. 2b.

A second approach in breast augmentation is to access the breast tissuethrough the inframammary fold adjacent the breast. In this case, aninframammary incision is made and the combination device is tunneledsuperiorly into the breast tissue to a position behind the breast. Inthe case of a subglandular implant, the combination device is tunneledthrough the pectoral fascia 14, creating a small tunnel through thefascia 14, while in the case of a subpectoral implant, the combinationdevice is tunneling through the deep pectoral fascia 28 between thechest wall and the pectoralis major muscle. (See FIGS. 2a and b).

A third approach is discussed in U.S. Pat. No. 5,258,026 to Johnson, thedisclosure of which is hereby incorporated by reference in its entirety,where an incision is made in the umbilicus and the combination device istunneled superiorly just above the fascia of the interior abdominal andchest wall and just below the subcutaneous tissue and fat. Uponapproaching the breast pocket, the surgeon will have the choice ofstaying either above the chest muscle and tunneling between the chestmuscle and the gland in the case of a subglandular implant or under thechest muscle and going between the chest muscle and the chest wall inthe case of a subpectoral implant.

Whichever approach is chosen from the standpoint of incision entrypoint, after the deflated balloon has been properly positioned in eitherthe subglandular or subpectoral position, the balloon is inflated byintroducing a suitable inflation medium, such as saline solution forexample, through a balloon inflation lumen into the interior of theballoon. The balloon is filled with a sufficient volume of fluid tocause the balloon to dissect tissue layers and create the desired pocketfor the implant.

Although some level of intra-operative expansion may be accomplished byfurther short term expansion of the balloon at pressures exceeding thevenous pressure, this is undesirable for several reasons. First,exceeding the venous pressure for an extended period may collapse thevenous system as previously described. Second, intra-operative expansionmay result in further tissue dissection at the margins of the dissectedspace, resulting in unwanted enlargement of the dissection footprintrather than further expansion in the anterior or Z-axis direction.During the long term tissue expansion step, it is desirable to monitorthe pressure of the balloon to ensure that the internal pressure doesnot exceed about 18 millimeters of mercury, as pressures in excess ofthis range may collapse the venous system, possibly leading to tissuenecrosis. To an extent, necrosis may be avoided by observing thephysical appearance of the tissue involved. In contrast, the pressuresrequired for dissection generally need not adhere to these limitsbecause dissection occurs over a very limited time and may exceed thevenous collapse limits by a considerable amount, depending on thedissection task. As a result of these greater pressures, some immediatetissue expansion and intraoperative tissue stretching may occur. Thepresent invention is not directed to such immediate tissue expansion,but rather to the combination of dissection and long term tissueexpansion.

It is to be noted that with traditional tissue expanders, an incisionoverlying the tissues to be expanded is made to insert the expander andthen after the expander is inserted, the incision must be allowed toheal to prevent the incision from being reopened by the force of thetissue expander. In contrast, the preferred combination device may betunneled in from a remote incision to a desired location where tissueexpansion is to occur. This allows immediate tissue dissection of thepocket and then immediate initiation of expansion without the need toremotely form a pocket or to permit a local incision to heal.

Several balloon constructions are useful in the design of combinationdissector/expander devices. Generally, it is useful to keep one side ofthe balloon relatively flat as it is gradually inflated, with the bulkof the expansion occurring to only one side. An illustrative examplemight be expanding tissue which overlies the rib cage for purposes ofreconstructing a breast. This sort of balloon behavior requiresnonuniform inflation characteristics. One embodiment of the combinationdevice may incorporate different thicknesses on balloon material tocontrol relative stretching and hence shape. In a balloon constructed oftwo flat sheets of the same material welded at their periphery, onesheet might be thicker, for example. In this case, progressive inflationwould stretch the thinner sheet preferentially. Different materials,i.e., weak and strong might be employed to achieve the same effect, asmay the use of a reinforcement, e.g., through the selectiveincorporation of fibers and/or fabrics which limits the stretching ofthe balloon. The balloon sheets may also be welded or laminated in orderto approximate monolithic sheets of nonuniform properties or thickness.In this manner, resistance to local stretching can be obtained whichwill alter inflated shape relative to shapes formed from uniform sheets(properties or geometry) of the same flat starting shapes.

Compound constructions may also be employed, for example, as in FIGS. 3and 4, where a structurally flat, "quilted" balloon is formed adjacentan open balloon. In such a construction, dissection may be carried outwith either balloon to create the desired pocket or footprint, thestructural balloon established, and then the expansion can progress fromthe footprint under controlled, periodic fluid increase.

In simple, one-balloon constructions, the fluid filler harness might besimilar to those used for balloon dissectors. After dissection iscomplete, the harness fittings could be removed, and a filler port,complete with self-sealing membrane attached to the filler lumen, andthe port implanted for the duration of the tissue expansion period. Withcompound constructions, either multiple filler lumens or a single lumenwith suitable valving may be employed. If it is desired to gain fluidaccess to two distinct balloons in a compound structure after skinclosure, then two implantable membrane ports may be utilized. If it isnot required to access the dissection balloon, only one membraneinjection port need be supplied, and the other lumen may be plugged orlocked off.

In order to relieve the pressure needed for dissection, but still retainthe relatively flat structure on one side at or below the tissuenecrosis limit, the inflation pressure may be relieved in accordancewith experimental results obtained which define the limits under whichpositive pressure in the balloon is retained even after significantfluid removal. Since the fluid pressure is the sum of the pressuregenerated by tissue elasticity and that from balloon elasticity,reducing the fluid pressure to the necrosis limit will assure that notissue damage occurs. When the pressure is reduced, if the balloon isinsufficiently rigid to maintain the flat shape additional stiffenersmay be used. For example, longitudinal stiffeners, wire or strips, orthe like, can be added in a parallel way which does not interfere withrolling or gathering of the deflated device in preparation for tunnelingwithin the body to the expansion site.

Another useful construction includes placing an expander inside adissector. In this construction, the dissected footprint may be greaterthan the footprint required for expansion, reducing the residual stressat the margins during expansion.

All constructions intended herein must be capable of rolling orcompaction to facilitate placement from an incision site remote from thetarget expansion site (or at least adjacent) in a manner which will notpromote tissue expander extrusion from the incision. Balloon covers, asdisclosed in application Ser. No. 08/570,766, may be utilized tofacilitate compaction of the balloon for tunneling.

It may be desirable to provide for balloon reuse, either to accommodateinspection/intervention between dissection and expansion, or to permitreuse of the device. If multiple insertions into the body arecontemplated, means may be provided to reattach the tunneling member tothe balloon if it is detached during any inflation step. A scope covermay be reinserted into the balloon to accommodate tunneling andvisualization, and if a guide rod is used, it may be reattached. Onereattachment method is to provide an external pocket at the distal tipof the balloon into which the end of the guide rod could be insertedrepeatedly. New or reusable balloon covers may also be provided, either,for example, by reuse of a separable semi-rigid cover, or by a new butseparate integral cover "sock" slipped over the rerolled balloon (orballoons in a compound construction).

A first preferred balloon 46 for an exemplary combinationdissector/expander is shown in FIGS. 3 and 4. FIG. 3 is a top view ofthe balloon 46 and illustrates welds 50 that are formed between thebottom and middle balloon layers 45 and 47, respectively, to form asemi-rigid inflatable base 44 for a purpose that will be explainedbelow. As best seen in the cross-sectional view provided in FIG. 4, thecombination dissector, sizer, and expander is preferably formed fromthree sheets of a material which is substantially inelastic over therange of pressures used to inflate the balloon. A thin sheet ofpolyurethane, exhibits suitable inelastic properties.

The bottom sheet 45 is bonded to the middle sheet 47 at the sheet outermargins by any suitable bonding system such as a heat sealing, forexample. The sheets 45 and 47 define an interior space 49 therebetweenwhich is in fluid communication with an inflation lumen 52 extendingfrom the balloon 46. Additionally, the bottom and middle sheets 45 and47 are bonded together at welds 50 at regularly spaced intervals overthe entire surface area of the sheets 45 and 47. The inflation lumen 52may be connected to a suitable balloon inflation source such as asyringe, for example. Although the balloon 46 may be inflated with air,saline solution is presently preferred.

Similarly, the upper balloon sheet 48 is bonded in a fluid-tight manner,such as by heat sealing, to the middle balloon sheet 47 to form aninflatable space 51 therebetween. The upper portion of the balloon 46 isinflated by introducing an inflation medium through the inflation lumen54 into the interior space 51 of the balloon 46. The lower base portion44 of the balloon 46 is semi-rigid and flat when inflated to facilitateoperation of the balloon 46 as a tissue expander. The base 44 is madesemi-rigid and flat in the manner of an air mattress, as shown in FIGS.3 and 4, such that the base of the balloon 46 has a consistent footprintin the dissected pocket. The consistency or regularity of the footprintis desirable to prevent the dissected pocket from being laterallyexpanded at its margins when the device is used as a tissue expanderafter dissection has occurred. By providing a semi-rigid base, theexpansion forces created by introducing the inflation fluid through thelumen 54 into the interior space 51 will be directed primarily in theanterior or Z-axis direction.

Several other techniques exist to restrict isotropic expansion of theballoon so that balloon expansion occurs primarily in the Z-axisdirection, i.e., the direction perpendicular to the footprint of thecombination device. In particular, a restraint may be provided bywelding members inside the balloon which will tether the sheets of theballoon at a fixed dimension. This technique is more applicable tofabricated sheet balloons than to blow-molded or melt-form balloons. Thetethering members may be baffles having finite length or may merely beintermediate welds between the facing sheets, as previously discussed.

In actual use, the balloon 46 may be rolled, folded, or otherwisecompacted and carried by one of the tunneling devices illustrated inapplication Ser. No. 08/570,766, for example. (In plastic surgeryapplications, the reusable devices disclosed in application Ser. No.08/570,766 are particularly desirable from the standpoint of cost). Thecombination device with the rolled, folded, or gathered balloon 46 isadvanced bluntly to a desired location within the body. A tissue pocketmay be created through dissection by introducing a saline solutioninflation medium, such as through the lumen 54 into the interior space51 defined by the top and middle balloon sheets 48 and 47, of theballoon 46. After the upper portion of the balloon 46 has been inflatedto create the tissue pocket, a predetermined amount of inflation fluidmay be withdrawn from the interior space 51 through the lumen 54 bysuction to achieve a proper volume for long term expansion.

If it is necessary to further expand the dissected pocket, the base 44of the balloon 46 is then inflated by introducing as inflation fluidthrough the lumen 52 into the interior space 49 defined by the middleand bottom balloon sheets 47 and 45, respectively. After the base 44 hasbeen inflated to provide a semi-rigid and well-defined structure lyingagainst the bottom or posterior side of the dissected space, the upperportion of the balloon 46 is again gradually inflated through lumen 54observing the appropriate pressure regimes utilized in tissue expansion.The balloon 46 is then left in the dissected pocket over a period oftime as a tissue expander. The internal pressure of the balloon 46 willneed to be periodically adjusted as the tissue gradually expands overtime. After the desired amount of tissue expansion has occurred, theballoon 46 may be removed by suctioning the inflation fluid from boththe upper interior space 51 and the lower interior space 49 throughlumens 54 and 52, respectively. The balloon 46 is then removed from thebody, and a suitable prothesis is implanted.

A second preferred balloon 60 for an exemplary combinationdissector/expander according to the present invention is shown in FIGS.5-9. The materials and construction of the balloon may be as describedin commonly assigned U.S. application Ser. No. 08/857,193 to Echeverryet al., filed on May 15, 1997, the disclosure of which is herebyincorporated herein by reference in its entirety. The inflated balloon60, as shown in FIGS. 5 and 6 may be in the shape of a square orrectangle with round corners as shown, or it may be circular orelliptical or any other desired shape suitable for the intended use.

As disclosed in Echeverry et al., the balloon 60 may be formed from twopanels of material defining a top 62 and a bottom 64 of the balloon 60.The top 62 and bottom 64 are fused or welded together around theperiphery creating a substantially fluid tight seam 66, as shown in FIG.7a and outer edge 68. Because the outer edge 68 may be rough or sharp,the seam 66 is preferably inverted such that the seam 66 is containedwithin the inflatable space 70, as shown in FIG. 7b. In other words, thepanels 62 and 64 are turned inside out.

An inflation lumen 72, similar to the inflation lumen 52 describedabove, is attached to the balloon 60 and is in fluid communication withthe inflatable space 70.

To prepare the balloon 60 to be carried by a tunneling device (notshown), for example, one of the devices disclosed in U.S. applicationSer. No. 08/570,766, the balloon 60 is compacted to facilitate itsinsertion to a desired location within the body. The preferredconfiguration is as follows. First, a distal portion 74 of the balloon60 is inverted into the inflatable space 70 of the balloon 60, as shownin FIG. 8. The side portions 76 are then rolled laterally inward ontothe top 62 surface of the balloon 60, as shown in FIG. 9. The invertedand rolled balloon 60 may then be rolled, gathered, or folded around atunneling shaft 78 or tube (not shown) of the tunneling device.

The combination dissector/expander utilizing the balloon 60 is used insubstantially the same manner as described for the dissector/expanderhaving balloon 46 described above. Upon inflation, the inverted androlled balloon 60 unrolls first, and then the distal portion 74 everts.Upon further inflation, the balloon 60 expands to create a dissectedanatomic space. The balloon 60 is then left in the dissected space overa period of time as a tissue expander.

The apparatus and methods disclosed above produce easy-to-use deviceswhich have economic advantages over use of separate dissection andexpansion devices used successively. Many combinations are possible, andthe combinations described are intended only to be illustrative of theinvention and not in any sense limiting. It will be understood by thoseskilled in the art that many changes in construction and widelydiffering embodiments and applications of the invention will suggestthemselves without departing from the spirit and scope of the invention.For example, the combination devices herein described may be used inwide variety of applications where naturally occurring potential spacesor tissue or planes occur in the anatomy. Thus, the disclosure and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

What is claimed is:
 1. A method of using an inflatable device to dissect a tissue pocket underlying the skin and to thereafter expand the dissected tissue pocket, the method comprising the steps of:providing an inflatable device comprising a balloon having an inflatable space, said balloon in an uninflatable and collapsed state having a distal portion inverted into said inflatable space and a side portion rolled laterally along a surface of said balloon; making an incision through the skin to access desired tissue layers; inserting the inflatable device into the incision; advancing the inflatable device between the tissue layers to a location where it is desired to create a tissue pocket; dissecting the tissue layers to create the tissue pocket by inflating the inflatable device with a fluid to a selected fill volume or pressure whereby inflation causes said side portion of said balloon to unroll and said distal portion to evert; reducing the fluid volume of the inflatable device to a level appropriate for long term tissue expansion; and gradually expanding the dissected tissue pocket by adjusting the fill volume of the inflatable device over a predetermined period of time.
 2. The method of claim 1 wherein the tissue pocket is created along a naturally occurring tissue plane by dissecting the pectoral fascia in a female breast.
 3. The method of claim 1 wherein the tissue pocket is created between a chest wall and a pectoralis major muscle.
 4. The method of claim 1 wherein the tissue pocket is erected between a pectoralis major muscle and a breast gland.
 5. The method of claim 1 wherein the incision is an axillary incision.
 6. The method of claim 1 wherein the incision is made in the inframammary fold adjacent a breast.
 7. The method of claim 1 further comprising the steps of:deflating the inflatable device; removing the inflatable device through the incision; and inserting a prosthesis into the tissue pocket.
 8. The method of claim 1 wherein the incision is made at a location remote from the location of the desired tissue pocket. 